Paint Calculator
Calculate approximate interior paint quantity while accounting for doors, windows, optional ceiling area and multiple coats.
Ceiling
Paintable area417 ft²
Area × coats834 ft²
Paint needed2.38 gal
Buy3 one-gallon cans
This uses 21 ft² per door and 15 ft² per window. Coverage depends on paint, surface texture, color change and application method.
How this tool works
Wall area = 2(length + width) × height minus assumed opening areas. Ceiling area is length × width. Multiply by coats and divide by coverage per gallon.
Example
A 14 × 12 ft room with 9 ft walls and two coats can be translated into gallons after subtracting doors and windows.
Common questions
How much area is assumed for doors and windows?
The calculator uses 21 ft² per door and 15 ft² per window as quick planning allowances.
Why might actual paint use be higher?
Porous surfaces, dramatic color changes, texture, overspray and product-specific coverage can increase usage.